Homebrew PCBs

Hi all,

I am currently using an upright vac with HEPA filter for my 
drill/rout table and was wondering what others use to keep the shop 
air clean ?

I am thinking of buying a large 12" x 12" filter and putting it into 
a box as the main filter as that would have a HUGE increase in 
surface area, at about the same price as a replacemnt for my vac.

Any bright ideas ?

Dave